Piston



are 9, 1943. c. E. s. KORYTKO 2 PISTON Filed Jan. 13, 1939 INVENTOR C. ES. KORYTKO .ATTYS. I

Patented Mar. 9, 1943 1' rrsron Charles Emile \Stanislas'Korytko. Paris, France; v vested in the Alien Property Custodian I Application January 13, 1939, Serial No. 250,826

- In Francelanuary 17,1938

'6 Claims.

This invention relates to pistons for engines and has for its object a piston which secures a satisfactory tight seal in an engine cylinder under all conditions of temperature in theengine operation.

It is known that the pistons which at present are in general use in internal combustion engines consists usually of. a casting which includes a,

rigid head where the piston rings are mounted, and a longitudinally split skirt which .is connected with said head in a manner enabling it to fit in. the best possible manner in thehcylinder in which the piston is mounted to operate.

Due to the thermal deformations the metal of the piston undergoes during the engine opera- .tion and the requirement that the skirt must .be. firmly connected with said head, difiiculties are found in obtaining a proper fit of the skirt in the cooperating cylinder both. when hot and when cold. The pistons at present in general use are subject to troubles such as either an unsatisfactory seal when cold or the liability of the giston seizing in the cooperating cylinder when at. The piston of this invention avoids such troubles in that'it includesa split skirtlwhich is entirely free in its region adjacent to thehead and is connected therewith in register with the skirt edge most remote from said head, the interconnection of said head and skirt being secured by means 'of a body or' arms which extend from said-head and provide bosses in which the .seats for the piston wrist pin are made.v

This invention also includes further features which make the piston skirt capable of deformation in a uniform manner and of acting as a seal band or segment.

An; embodiment of the present invention is illustrated by way of example on the annexed drawing and Fig. 1 is a central longitudinal sectionmade I on line'I-I 'ofFig. 2;-

Fig.2 is a central longitudinal section;on line 2-2ofFig.1;--

d Fig. 3 is a transverse section on. line 3-3 of Fig. l; d

Fig. 4 Fig. 1;

Flg'. 5 is a transverse section on line 5-5 of Fig. l. d I 1 In the construction illustrated, the piston in is a transverse section on line 4-4 of -cludes a head I'having; as usualy'grocves 2 intended to receive usual piston rings, not shown.

Two arms 3 extend from the head I in diametrically opposed regions thereof, and provide seats 5 for the piston wrist pin, not shown.

A piston skirt 1 encircles said arms 3 and has an edge adjacent to and spaced from thepiston head I, and an opposed edge which. is remote from said head. Said skirt I has its last named (Cl. zoo- 11) edge connected at 6 with theiree ends of the bosses 3 and its outer surfacee itends in reg ister with the side surface of the head I while the first named edge of the skirt 1 is' entirely gseparatedirom. the pistonl due to the annular gap 3 provided intermediate saidhead and skirt. A longitudinal slot l0; which preferably is inclined as shown, extends "throughout the skirt I as shown inFig. 1. d 10 Owing .to the described arrangement, the skirt I is independent of the head I to the maximum possible extent and it is free to expand and contract; said skirt is thus able toprovide a satisfactory alignment of the'piston in the cooperating cylinder under all conditions as may occur in operation without the piston being subject to seizure in the cylinder. Due; to the fact that the head I is connected withbosses 3 having a comparatively large cross section, the heat accumulating in the head I may dissipate through said bosses 3 into the skirt 1 which is inintimate contact with the wall of the cylinder, this wall in turnbeing cooled" by the usual cooling means provided in internal combustion engines.

Further, due tothe fact that the skirt 1 and the internal parts of the piston are interconnected adjacent their end remote from the head, said skirt 'l has its coldest region adjacent ,to

- the piston-head, contrary toconditions prevail ing in known constructions.

' The above stated; conditions enable a cylin drical shape to be imparted to the outer surface of said skirt 1 instead of a conical or tapering shape, as usual. The machining is thusrnade more easy and the adjustment of the piston within the cooperating cylinder and also the possibility for mounting it with'a somewhat ,forced fit are' secured.

Thepistcn is preferably made of a light metal alloy but it may be made of any preferred metal onaccount of the fact that the effect of heat expansion is reduced to' a minimum dueto the described construction of the piston.

square inch against .the cylinder wall has a minimu mvalue.- v

A number of rings usually provided in the pis- I ton may then be omitted and consequently the wear of thecylinderwall surfacev due to the piston rings is reduced while also the longitudinal size and weightof the piston head are lessened? the dynamic balance of the pistonmay' thus be improved and accordinglythe total longitudinal A sealing ring I8 may be located in the gap 9 extent of the piston may be reduced without i To fully avail of the material providing the intemal'parts' of the piston such a shape and.

size may be imparted to bosses 3 as to supply a resiliency proper toenable the lower region of the skirt to develop an appropriate pressure as afforded by the expansion of the piston head. 7

For such a purpose a shape of uniform -resistance is imparted to the bosses 3; accordingly the thickness of the bosses may be caused to decrease starting from the piston head i as shown in Fig. 1 or the width of said arms may s be decreased as shown in Fig. 2;

.The bosses .3 connect with the lower edge of the skirt I at a region 6, which preferably is extended in a direction perpendicular to the generatrix lines of the cylindrical skirt and the sectional area of the arms and of the connect ing' regions are calculated in such a manner as to secure a stiflness sufiicient to hold the axes of the head I and of the skirt l'coincide'nt with .each other. n Theconnecting region Gis more extensive on,

one side of the piston, as shown at 6"in Fig. 2 than on the other, and the extension 6' is located on the side where the skirt 7 has its longitudinal slot ID, as shown in Figs. 3-5. The resiliency of the bottom portion of the skirt is thus uniform over the full circumference thereof.

It is useful for the 'wailproviding the skirt 1 to have a larger thickness in the portion thereot adjacent to the piston head than at the opposed end, as'shown in Figs; 1 and 2; by this provision the differences in resiliency as may dependon the interconnection of the skirt 1 with the bosses 3 are compensated for, whilst a fully cylindrical outer surface may be obtained. v

A varying thickness may be imparted with advantage to said skirt also in respect of the trans-;

deformable skirt spaced from said head and connected thereto, said skirt being slotted, and two struts'having aligned wrist-pinbores therein extending from peripheral portions o1 said head, each of said struts being connected at its end with said skirt on the ,edge thereof which is remote from said head, the connecting region of said skirt and each of said struts extending along an arcof said skirt edge and being enlarged at that side of each of said struts which is adjacent to the slot of said skirt.

' 3. In a piston comprising a rigid head and a deformable skirt spaced from said head and connectedtthereto, said skirt being slotted, said skirt having an outer cylindrical surface and a thickness decreasing from theskirt edge adjacent to said head to the skirt edge remote from said head, and two struts having aligned wrist-- pin'bores ,therein extending from peripheral portions of said head, each of said struts having a cross section at one end elongated circumferentially'of said skirt, and being connected at its verse sectionthereof, to secure a uniform resiliency throughout said skirt. 7

In the embodiment shown the transverse section of the'skirt has a maximum thickness in the region l9 thereof which is opposite the slot l0, and said thickness decreases as the slot edges are'approached. a

The above described arrangement imparts to said skirt such a uniform resiliency as to develop an even pressure on the cylinder walls and to provide for a no-play fit in the cylinder when cold as an eifect ofthe expansion of said skirt. Further the expansion of the skirtwhen hot is compensated for by its'freedom to contract, any possibilityof the piston becoming seized in the cooperating cylinder being removed, because the pressure the piston skirt may, develop on the cylinder wall cannot go over a determined value. p

What I claim secure by United States Letters Patent is: k ,1. ,In a piston comprising a rigid? head and a deformable skirt spaced from said'head and connected'thereto, said skirt being slotted, and two struts having aligned wrist-pin bores there'- in extending from peripheral portions of said head, each of said struts having a cross section 'at one end elongated circiimferentially of said skirt, and being connected .at its circumferent'ially elongated end with said skirt on the edge thereof which is remote from said'head.

2. In a piston comprisinga rigid head and a as my invention and desire to circumferentially elongated end with said skirt on the edge thereofwhich is remote from said head.

4. Ina piston comprising arigidhead ands. deformable skirt spaced from said head and connected thereto, said skirt being slotted, said skirt having a thickness varying graduallyfrom a maximum in the skirt portion diametrically opposite to the skirt slotqto a minimum at the,

slot edges, and twostruts having 'aligned wristpin bores therein extending from peripheral,por tions of said head.:each of said struts having a cross section at one end elongated circumferentially of said skirt, and being connected at its circumferentially elongated end with said skirt on the edge thereof which is remote from said head. i l

5. In a piston comprising a-rigid,;head and a deformable skirt spaced from said head by an intermediate continuous gap and connected thereto,-said skirt being slotted, a ring located in. said gap andclosing the aperture of said slot in said gap, and two struts having aligned wristpin bores therein extending from peripheral portions of said head, each of said strutshaving a cross section at one end elongated circumferencircumferentially elongated end with said skirt on'the edge thereof which is remote from said head.

6. Ina piston comprising a rigid head and a deformable skirt spaced from said head and connected thereto, said skirt being slotted, said skirt having an outer cylindrical surface and a thickness decreasing from its edge adjacent to said head to its edge remote from said head, said thickness also varying in different regions of the skirt transverse section from a maximum in the skirt portion diametrically opposite to the slot to a minimum at the slot edges, and two struts having aligned wrist-pin bores thereinextending from peripheral portions of said head, each of said struts being connected at its end with ,said skirt on the edge thereof which is remote from said head, the connecting region of said skirt and each of said struts extending along an arc of said edge, and being enlarged at that side of each of said struts which is adjacent to theslot oisaid skirt.- v

, memesism KQBYTKO. 

